The present invention relates to a new and improved method of, and apparatus for, the so-called long-term pressing of printed products, especially newspapers. At times throughout this disclosure reference to such method and apparatus will be simply generally made in terms of measures for accomplishing such long-term pressing of the printed products. Equally, while the description to follow, as a matter of convenience, refers to the processing of newspapers, obviously other types of products can be conveniently handled and therefore the use of this term is not to be construed in a limiting sense in any way whatsoever, merely is to be viewed as an exemplary and desirable field of application for the inventive measures.
During the processing of printed products, especially newspapers, there are repeatedly encountered difficulties because such products constititute irregular or non-uniform structures and, in any case, possess or develop properties which, notwithstanding the product uniformity which might be attainable during the production of the products, results in an irregularity or non-uniformity of the products at a later point in time. This is attributable to a considerable degree to the fact that paper constitutes so-to-speak "living" material, i.e. a material which tends to "work", and thus its corresponding properties tend to be particularly perceivable when the paper is used for forming a multi-sheet folded product. Attempts have been made to counteract this phenomenon by resorting to a pressing action exerted upon the products. To that end, the paper products were passed between press cylinders or press rolls which, if desired, also could possess a profiled jacket or outer surface. However, this technique only afforded a pulse-like pressing action which while in most instances resulted in a momentary improvement in the properties of the product did not however eliminate the actual origin of the problem. This is equally the case even if the products are passed a number of times between press cylinders or press rolls. After each pressing operation the residual stress or residual elasticity of the products caused the prior processed product to tend to restore to its original characteristic, especially at the region of the product spine. Consequently, the strived for uniformity in the products was lost or, in a worse case situation, not even attained at all. To preclude the undesirable effects of the residual stress or residual elasticity of the products it would be necessary to subject the products to a pressing action for such a long period of time that no restoring forces are retained any longer in the paper. Yet, this is not possible in those facilities where the product is fabricated or processed, particularly if it is kept in mind that when processing printed products many tens of thousands of product copies must be produced or processed every hour and then frequently twenty-four hours of the day. A further factor worthy of mention is the reality that when dealing with printed products, especially newspapers, periodicals or the like, the contents thereof are short lived, i.e. the newsworthy or other items of interest contained therein usually only have a limited period of time where they are of interest to the reader, and therefore for that reason alone the products cannot be subjected to a pressing pressure or compresive forces which requires any excessive amount of time. This is also true for the so-called preprinted products, i.e. for those product sections which are printed ahead of time and until they are united with the actual newsworthy portion of the printed product are stored in an intermediate storage area. Additionally, even in the case of the pre-printed products, if it were intended to make use of this available storage time for exposing such pre-printed products to a pressing action over a longer period of time, nontheless there would be required an appreciable expenditure in equipment to achieve this result.